I have a 100,000 btu boiler in my shop and 100,000 btu furnace in my house. The one in the house burns perfect. Nice clean pot sides, nice hard white clinkers and low ash, and very efficiant. My problem is the boiler in the shop. I am always getting clinkers stuck to the side of the pot and always have big globs of black ash coming out of the pot. The inside of the burn chamber is pure black and i usually have smoke coming out the exhaust that smells like when the fire is left to burn out. When i open the door on high fire i get a flame that comes out the door then goes back in. But then when its on low fire it burns down too low in the pot. My timer is at 2.5 and 8 and draft at .04. Auquastat is at 170 low and 195 high. Combustion air is about 1/4 open. Im burning the exact same corn in both stoves. Any idea what my problem is with the boiler?

What is the temp of the water returning to the boiler?

I have everything set so the water returning to the boiler through the primary loop is about 10 to 15 degrees less than the water comong out which is around 160

Well....it sounds to me like your fire is low on heat. I would "soup it up" a little by cutting your "off" time back to 6 and try that. If your fire is low in the pot you are also short on fuel and shortening the time off will help that also. You must have nice dry corn because it is burning down with just the draft and not any combustion air. You may need to open the gate on your combustion blower a little too but make only one change at a time and give it a few hours to see what changes, re-diagnose, and make necessary changes and wait again. Good luck-CC

I have a 100k boiler also I can't tell you enough to make sure flue tubes are clean I know this sounds wrong but last year I fought with mine half the year was on speed diel with Mike in Wisconsin finally i shut it down are removed the top to look down the tubes they were 3/4 plunged and the brush didn't clean it out get a 1 3/8 hole saw and add a 20 inch rod to it and use a drill to cut down though the tubes to get them clean will make a Hugh difference burned lick new again hope it helps

I have tried changing my combustion fan and it does burn lower on high fire but i still get big popcorn ash balls and the inside of the stove is pure black.What is causing all the clinker build up on the pot? It seems like they are blcking the air and causing some of my high fire problems. I am going to take the top off today and see what it looks like. Like i said, i am burning the same corn in both stoves so the corn is not the issue

UPDATE**** I wedged my draft cotroll shut so the fire would burn out faster today to clean the stove. When i came back i had a layer of clicker all the way around the pot so hard that i had to use a chisel to get it off. And the inside of the stove was starting to turn white again instead of black

UPDATE**** I wedged my draft cotroll shut so the fire would burn out faster today to clean the stove. When i came back i had a layer of clicker all the way around the pot so hard that i had to use a chisel to get it off. And the inside of the stove was starting to turn white again instead of black.

that sounds just like my boiler did last year before i got the tube really clean if it can't breath the water doesn't get hot enough so the aqua-state calls for heat the heat can't get out so the corn starch get really hard plus it doesn't breath good so that is where the popcorn comes from not enough air you just need to make sure the tubes are clean and don't take for granted that the brush is doing the job look though the tube with you're own eye

Thanks. Found the problem. Apparently i didnt take the top off and clean it this spring like i usually do. (most likely because spring and planting came so fast this year.) I had cleaned the tubes from to bottom this year but there was too much laying on the top.

Anyone know where i can get one of them spiral cleaners for the tube like i have seen on here? I dont really like the idea of the hole saw.